Modify the query on custom post type archives

custom_pt_modify_loop

add_filter( 'pre_get_posts','add_to_query' );
function add_to_query( $query )
{
    if ( is_post_type_archive( 'listings' ) ):
        $query -> set( 'orderby' , 'title' );
        $query -> set( 'order'   , 'asc' );
    endif;
    
    return $query;
}